Uriel exchanged a glance with Zadkiel when Lucifer made a (rather large and unpleasant looking) sword appear. Neither of them had a chance of defeating Lucifer in a one-on-one fight. Two-on-one was not looking much better. The best they could do was keep him distracted and try to dodge.
Uriel swung at Lucifer's back as the Morningstar rushed Zadkiel, the flames from his sword creating a bright, fiery arc as he moved.